Piston



April 27 1926.

. R. V. PALMER PISTON Filed Deo. 5, 1925 TTORNE'IT Patented Apr. .27, 1,926.

UNITED STATES 1,582,426 PATENT OFFICE.

RALPH V. PALMER, OF ST. PAUL, MINNESOTA,

rIsroN.

Application led December 5, 1925. Serial No. 73,369.

pistons for explosive type engines and the main object is to provide a piston of certain construction and means for expanding the major part of the piston walls to provide take-up when a piston has become worn by its reciprocating movement, thus prolonging the life of a piston.

In the accompanying drawing:

Fig. 1 is a side elevation of a piston of my improved form.

Fig. 2 is a bottom view of Fig. 1.

Fig. 3 is a vertical central section of the piston about as on line 3--3 in Fig2.

Fig. 4 is also a vertical section about as on line 4-4 in Fig. 2.

Referring` to the drawing by reference numerals, I have Vshown a preferred type of light-weight piston 5, having the usual solid web 6 at the upper and compression end nf the piston. The barrel ofthe piston comprises an upper section with piston-ring retaining grooves 7 for Hrings 8, and a lower circular or ring section 5L from which, at opposite sides, -an apron 9, extends upwardly and terminates near head 5T. The lower ringL and aprons 9 are turned to approximately the same diameter as head 5T and said parts are provided with grooves 10 or so called oil grooves to spread lubricating oil on the piston and cylinder walls. A

Between the opposite aprons 9 I provide two horizontally spaced vertical walls 11 in which are bosses 12 bored for retaining the usual wrist pin 13 for the upper end of 'the connecting rod 14 (the latter shown dotted in Fig. 3) Said walls are cast integral with and project downward from the head end 5T leaving horizontal openings 15 (Figs. 3 and 4) between the walls 11 and ring 5".

16 are two slits cut longitudinally of the piston and extending from its lower end at diametrically opposite sides of the piston up to a horizontal slot 17 below head 5T, thus dividing that part of the entire piston below head 5T into two semi-circular aprons each comprising one half of the opposite areas 9 and the adjacent half of ring 5L.' These two parte will hereinafter be termed the aprons of the piston. These aprons are because of the vcuts 16 capable of being expanded diametrically to a certain extent and thus take up wear caused by the reciprocating movement of the piston in the engine cylinder (not shown). It will bev understood that my piston is cast with thin drical walls below head 5T.

18 are two segmental vertically disposed plates each with an outwardly directed flange 18A at its upper end and adapted to lrest on the piston wall at the lower edge of slotl 17. The body of each plate therefore is suspended by its flange and normally engages the inner wall surface of the piston preferably to a. line below the center of the ring 5L. The two plates are thus diametrically opposite each other and by spreading them from each other the two aprons are forcedoutwardly and enlarge thediameter of the said parts of the piston. This spreading is done as follows:

One plate 18 has an upper pair of parallel threaded-rods 19 each suitably fixed as in a boss 2O at the inner side'of the plate. The opposite plate has two parallel tubular members 21 suitably fixed to the inner side and each registering horizontally with a rod 19 for slidable insertion ofthe latter into its bore. 22 is a nut on the threaded part of cylineach rod 19 and adapted to bear against the Y inner side of tube 21. Thus by manipulating these lnuts the threaded rods 19 are forced outwardly from the tubes and the opposite plates 18 are forced apart andfcause thefaprons to spread. The lower parts of the plates 18 are likewise provided with a pair of rods 19, sleeves 21 and nuts 22 for 4spreading the lower parts of the aprons.

It is obvious that one pair of rods 19 and cooperating parts may be used in short types of pistons. As a lrule the normal amount of spreading required is only a few thou# sa-ndth parts of an inch and therefore the diametral strain on the aprons is so slight as not to effect the solidity of the piston.

What I claim is:

1. A piston of the class described comprising a tubular body with a solidweb at one end and open at the other end, wristpin retaining means intermediate said ends, said piston having two diametrically opposite horizontal slots and slitted longitudinally from the center of each slot to the open end of the piston and meansfor spreading the parts of the piston between said horizontal slots and the open end, Said expanding means comprising mainly two segmental plates each with an upper outwardly directed flange adapted to engage in one of the horizontal slots and the main body of each plate of a curvature to tit the inner surface ofthe tubular piston and extending approximately to the lower end of the piston.

Y2. The structure specified in claim 1, and

` a number of horizontally disposed spreading elements for said plates, each said element comprising a fixed tube suitably secured to one plate, a horizontally registering threaded rod suitably fixed to the oppositeV plate and adapted to be slidably with a closed head end and slitted longitudinally belowl said head end to form a number of cireularly arranged depending aprons, removable outwardly flanged means engaging'4 horizontal slits in the Walls of the piston and horizontally extensible meansl connecting said flanged means to expand the aprons diametrieally simultaneously as set forth.

In testimony whereof I atlix my signature.

RALPH V. PALMER. 

